Semisubmerged ship with hull extensions

ABSTRACT

An improvement for the semisubmerged ship provides hull extensions for additional buoyancy or increased cargo and fuel storage which do not appreciably create more drag. In one configuration sacks disposed below the level of surface wave action are inflated to permit shallow water operation. Preferably, however, the hull extensions have a meniscoidal cross-sectional configuration and are mounted on the submerged hulls. Particularly in the case of the meniscoidal-shaped extensions, the structural integrity of the semisubmerged ship is not compromised and the ship&#39;&#39;s capability for high-speed operation remains substantially unimpaired since the hull extensions do not appreciably create excessive drag. Whatever configuration is chosen, the hull extensions are either permanently or releasably coupled to the hulls to allow flexibility in range and payload.

[451 Aug. 20, 1974 SEMISUBMERGED SHIP WITH HULL EXTENSIONS [75]Inventor:

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

[22] Filed: Apr. 26, 1973 [21] Appl. N0.: 354,555

Thomas G. Lang, San Diego, Calif.

[52] US. Cl. 114/61, 114/49, 114/.5 F [51] Int. Cl B63b 1/32 [58] Fieldof Search 114/49, 52, 53, 54, 61,

114/123, 16 E, .5 F, .5 R; 9/1 R, 6

[56] References Cited UNITED STATES PATENTS 1,316,357 9/1919 Cook114/123 1,861,338 5/1932 Faust 114/61 2,361,949 11/1944 Langdon 114/16 E3,171,377 3/1965 Livas 114/49 3,198,157 8/1969 Livas 114/49 3,623,44411/1971 Lang 114/61 3,626,881 12/1971 Lovingham 114/16 E 3,665,5325/1972 Simpson 9/6 3,726,245 4/1973 Critcher 114/.5 F 3,732,587 5/1973Fletcher 9/6 3,760,754 9/1973 Drummond et al. 114/.5 F

Primary Exar'niner-George E. A. Halvosa Assistant ExaminerEdward R.Kazenske Attorney, Agent, or Firm-Richard S. Sciascia; Ervin F.Johnston; Thomas G. Keough [5 7 ABSTRACT An improvement for thesemisubmerged ship provides hull extensions for additional buoyancy orincreased cargo and fuel storage which do not appreciably create moredrag. In one configuration sacks disposed below the level of surfacewave action are inflated to permit shallow water operation. Preferably,however, the hull extensions have a meniscoidal cross-sectionalconfiguration and are mounted on the submerged hulls. Particularly inthe case of the meniscoidalshaped extensions, the structural integrityof the semisubmerged ship is not compromised and the ships capabilityfor high-speed operation remains substantially unimpaired since the hullextensions do not appreciably create excessive drag. Whateverconfiguration is chosen, the hull extensions are either permanently orreleasably coupled to the bulls to allow flexibility in range andpayload.

3 Claims, 13 Drawing Figures PATENTED SHEHIUF 2 FIGS SEMISUBMERGED SHIPWITH HULL EXTENSIONS STATEMENT OF GOVERNMENT INTEREST The inventiondescribed herein may be manufactured and used by or for the Governmentof the United States of America for governmental purposes without thepayment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The semisubmerged ship for which thisinvention is an unobvious improvement, is thoroughly described in U.S.Pat. No. 3,623,444. Briefly, the semisubmerged ship places one or twohulls well below the area of surface wave action and supports a platformabove the water by at least one water surface piercing strut member.Horizonally oriented stabilizers, vanes and canard fins are mounted onthe hulls to ensure high-speed dynamic pitch, roll, and heave stability.However, one limitation of the semisubmerged ship became apparent inthat the maximum buoying force was a fixed function governed by thedimensions of its submerged hulls. Thus, its maximum range was limitedby the amount of fuel that could be carried and its maximum payload wassimilarly restricted. One obvious solution would be to build asemisubmerged ship with larger hulls. On shortrange routine operationsthe larger hulled ship would be inefficient when compared to a shiphaving smaller hulls specifically designed for short-range orreducedpayload applications. Therefore, in semisubmerged ship design aneed for an increased buoyancy and payload while not apprciablyincreasing the drag continues to exist. Structure and devices toincrease the buoyancy of a surface craft or to reduce its drag are manyand varied in design. For instance, U.S. Pat. No. 6469 issued to AbrahamLincoln in 1849 directly addressed itself to reduce the draft ofsteamboats. Expandable chambers were connected to the sides of thesteamboat to buoy it over shoals. The expandable chambers were placed inthe area of surface wave action to greatly increase the ships drag andhence render such a modification unsuitable for the high speedsemisubmerged ship. While this approach may represent a noteworthymodification for surface ships, taken in light of the state oftechnology at the time, history has proven that the inventor could anddid better devote his talents to other fields of endeavor. Two othermore recent attempts to reduce a ships draft are shown in two U.S.Patents to Livas. These U.S. Pats, No. 3,171,377 and 3,198,157 show theuse of an inflatable flexible membrane or the attachment of buoyantchambers to the side of the hull. Either approach mounts the buoyancyelements in the area of surface wave action and turbulance and seriouslyeffects the ships manueverability and drag. Others have tried securingpontoons onto the sides of a ships hull to reduce draft. Here again, thebuoying members are located on the surface of the water and by being solocated impose intolerable speed and manueverability limitations.

SUMMARY OF THE INVENTION The present invention is directed to providingan improvement for a semisubmerged ship having at least one hulldisposed beneath the waters surface, a platform carried above the waterssurface, and at least one water-surface piercing strut memberinterconnecting the hull and platform. A means for increasing the volumedisplaced by the semisubmerged ship is located well beneath the area ofsurface wave action and is secured in place by a mounting means whichensures increased displacement while not introducing excessive drag.

It is a prime object of the invention to provide an improvement for thesemisubmerged ship.

Another object is to provide for increasing the payload and range of thesemisubmerged ship.

Still another object is to provide for hull extensions carried below thearea of surface wave action to ensure greater payload.

Still another object is to provide hull extensions configured forincreasing the semisubmerged ships buoyancy while not overlycompromising drag.

Still another object is-to provide an improvement for the semisubmergedship giving the ship a reduced draft.

Yet another object of theinvention is to provide for hull extensionswhich simultaneously provide increased buoyancy, increased range, andincreased protection for the semisubmerged ship.

These and other objects of the invention will become more readilyapparent from the ensuing specification when taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are isometric depictionsof two typical examples of the semisubmerged ship showing the hullextensions in place.

FIGS. 3a and 3b schematically in cross-section show one embodiment ofthe invention taken generally along lines a-a in FIGS. 1 and 2.

FIGS. 4a and 4b schematically in cross-section show another embodimentof the invention.

FIG. 5 shows still another embodiment of the invention.

FIG. 6 shows yet another embodiment of the invention.

FIGS. 7, 8, 9, and 10 show the preferred configuration of the invention.

FIG. 11 shows typical mounting positions of the hull extensions.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2of the drawings, the semisubmerged ship is depicted in two typicalembodiments each having one or more hulls 10 disposed one or more hulldiameters below the surface of the body of water. At least onewater-surface piercing strut 11 extends upward from a hull to support aplatform 12 above the waters surface and, in the embodiment of FIG. 2, apair of water-surface piercing strut members 13 depend from oppositelateral extremes of the platform into the water.

Horizontally oriented stabilizers 14 having a rectangular configurationin FIG. 1, or a delta configuration in FIG. 2, and canard fins 15 aremounted on the hulls a distance below the area of surface waveturbulance. The struts, horizontally oriented stabilizers, and canardfins hydrodynamically cooperate as the semisubmerged ship makes a highspeed run to ensure the vessels stability in dynamic pitch, roll andheave. These two representative examples possess superior dynamic andstatic stability. Suitable control and drive mechanisms suitablyarticulate the canard fins and stabilizers and additional flaps, ventsetc. optionally are included to ensure such stability.

Inclusion of the hull extensions 20 has resulted in these designs havinga significantly increased payload and range without adding excessivedrag or impairing the vessels manueverability.

Increased buoyancy is provided for by the hull extensions which may beone of a variety of configurations. Irrespective of which configurationis chosen, it is important to place the extensions well below the waterssurface. Laboratory tests have indicated that such placement reduces theproblems associated with surface wave action e.g., excessive drag andimparied maneuverability.

One embodiment of the hull extensions is shown in FIGS. 3a and 3b. Aninflatable sack 21 is carried on a submerged hull while anotherinflatable sack 22 is mounted on a strut. Both the sacks are locatedwell below the area of surface wave action and do not introduce theproblems attendant surface wave interaction. The sacks are fashionedfrom a heavy, flexible material such as rubber impregnated canvas or aheavy duty plastic sheet. In any event the sacks are selectivelyinflatable by a source of pressurized gas 23 interconnected byconventional piping to inflate the sacks when an increased buoyingcapability is called for. The flexible sacks are bonded or otherwisesuitably secured onto discrete portions of the hull and the struts maybe tailored to run the entire length of the hull depending on the degreeof buoyancy wanted. High speed operation is somewhat impaired because ofthe sacks flexibility. Another drawback of using flexible sacks is thatthey are constantly exposed to external damage especially when thesemisubmerged ship is operating near docks and piers. Damage fromroutine abuse also tends to shorten the sackss useful life.

One attempt at reducing the flexible, inflatable sacks vulnerability todamage is shown in the embodiment of FIGS. 4a and 4b. Here, a source ofgas 23 is connected to a flexible, inflatable sack 21 of the typereferred to above and which is carried inside a curved cover plate 24joined to the hull by a hinge 24a and a latch 24b. When occasionalbuoyancy is needed, for example, when the semisubmerged ship is enteringa shallow harbor, or passing over a reef, gas from source 23 is ventedto inflatable sack 21 after latch 24b has been released. Cover plate 24is rotated in a clockwise direction about hinge 24a as the sack fillswith gas. In this embodiment it has been found expedient to secure thesack to the inner surface of the hinged cover plate so that when thesack is inflated the cover plate is automatically rotated to release thesack, and later, when the sack is evacuated, it pulls cover plate 24back against hull to be securely engaged by latch 24b.

Another modification employing a flexible flotation member is shown inFIG. 5. An elongate resilient sleeve 25 is gripped at opposite ends bylarge ring-like clamp members 26. A source of pressurized gas, not shownin FIG. 5, is selectively vented to the interior of resilient sleeve toproduce the desired degree of supplemental buoyancy.

The use of flexible sacks or sleeves is not entirely satisfactory forhigh speed operation. The high water-flow rate over the flexiblesurfaces causes fluctuation and other flow related consequences.

In addition the flexible devices are vulnerable to puncture and tearing.

An alternate mode of construction of the embodiment of FIG. 5 calls forsubstituting a rigid toroseshaped sleeve 25 in place of an inflatableresilient sleeve 25. Mounting a rigid sleeve does avoid the flexiblesleeve problems yet it introduces some of its own, particularly when thesleeve is mounted on the external surface of hull 10. If the sleeve isan integral unit, canard fin 15 would have to be disassembled duringinstallation and removal. If the rigid sleeve is separated intolongitudinal sections an improved design, discussed below, would betterserve the anticipated needs.

Another modification for giving a semisubmerged ship a variable buoyancycapability is shown in FIG. 6. A telescoping section of hull 10 isconcentrically extended by an internally carried rack and pinionmechanism, not shown for the sake of simplicity in the drawings.Suitable seals are included to prevent the flooding of the hulls andpressurized gas is vented to the interior of the extended hull to reducethe possibility of flooding.

The preferred embodiments for providing the increased buoyancycapability are shown in the variety of hull extensions schematicallydepicted in FIGS. 7 through 10. These hull extensions optionally extendpart-way or alI-the-way on opposite lateral sides or on only one side ofa hull, see hull extensions 30 in FIG. 11. In the embodiment of FIG. 7 asingle solid extension 31 is shaped in a meniscoidal configuration withan inner surface fitting around the circular hull l0 and with an outersurface shaped to hydrodynamically cooperate with the surrounding water.

In this embodiment the hull extension is a rigid material having adensity less than water to provide a buoying force. Wood, polyeurthanefoam, and other equivalent materials may be used. In this regard amaterial which affords a degree of protection from underwater ordnanceor submerged obstacles would be the best choice.

The meniscoidal hull extension is releasably connected by a plurality ofbolts 32 or any other suitable connecting means. Using bolts or anequivalent releasable connector, gives a semisubmerged ship an immediatevariable buoyancy capability. If a task calls for a greater payload,then meniscoidal hull extensions having a larger cross-sectionalconfiguration are mounted on the hull. Considerable mission flexibilityis assured by having several sets of hull extensions on hand. None ofthe herein described extensions compromises the ships structuralintegrity yet all give added buoyancy and protection for the hulls.

The meniscoidal shaped extension, while greatly increasing the hullsbuoyancy does not create an excessive amount of drag or impair thevessels maneuverability. Experimental test data indicates that the dragcoefficient does not change appreciably with the increased buoyingcapability. That is to say, by example, the drag was increased no morethan 10 percent with a 30 percent increase in displacement.

The embodiment of FIG. 8 includes two rigid meniscoidal hull extensions31 also secured in place by bolts 32 or equivalent means. The two hullextensions create more buoying force and present a symetrical hull whichreduces control and trim problems, particularly in the single hullsemisubmerged ship.

The embodiment of FIG. 9 has essentially the same cross-sectionalconfiguration as the embodiment of FIG. 8 but meniscoidal hullextensions 31 are 31 are hollow and are compartmented to allow for theStorage of fuel, supplies, ordnance or to function as buoyancy chambersdepending on what is needed. Here again, the hull sections arereleasably coupled to the hulls by bolts 32 to give the ship a variablebuoyancy.

The embodiment of FIG. shows a combination of a rigid meniscoidalextension 31 and a compartmented meniscoidal extension 31' carried on anelliptical hull 10. When a twin hull semisubmerged ship is so modified,the rigid hull extension is placed on the outside to further protect thehull while providing buoyancy.

Particularly with respect to the embodiments of FIGS. 7, 8, 9 and 10data has demonstrated that for a given increase in buoyancy the dragdoes not appreciably increase. The semisubmerged ships structuralintegrity remains, it not sacrificed irrespective that the ships rangeand payload have been greatly increased.

surface piercing strut member, interconnecting the hull and platform, animprovement therefor is provided comprising:

a pair of means for increasing the volume displaced by saidsemisubmerged ship each disposed on opposite sides of said hull andhaving a rigid meniscoidal cross-sectional configuration with its innercontour shaped to accommodate said hull and its outer contour shaped toreduce the problems associated with drag, a first one of the increasingmeans has at least one compartment for buoyancy and storage and a secondone of the increasing means is filled with a rigid buoying material forbuoyancy and protection of the hull and both of the increasing meanscooperate to give the composite structure created thereby an ellipticalcross-sectional appearance, and;

means for removeably mounting both increasing means beneath the waterssurface on said hull to give said semisubmerged ship a variabledisplacement.

2. An improvement according to claim 1 in which at least one of theincreasing means extends nearly the full length of said hull forproviding increased buoyancy and protection thereto.

3. An improvement according to claim 1 in which at least one of theincreasing means extends only a fraction of the length of said hull.

1. In a semisubmerged ship having at least one hull disposed beneath thewater''s surface, a platform carried above the water''s surface, and atleast one water-surface piercing strut member, interconnecting the hulland platform, an improvement therefor is provided comprising: a pair ofmeans for increasing the volume displaced by said semisubmerged shipeach disposed on opposite sides of said hull and having a rigidmeniscoidal cross-sectional configuration with its inner contour shapedto accommodate said hull and its outer contour shaped to reduce theproblems associated with drag, a first one of the increasing means hasat least one compartment for buoyancy and storage and a second one ofthe increasing means is filled with a rigid buoying material forbuoyancy and protection of the hull and both of the increasing meanscooperate to give the composite structure created thereby an ellipticalcross-sectional appearance, and; means for removeably mounting bothincreasing means beneath the water''s surface on said hull to give saidsemisubmerged ship a variable displacement.
 2. An improvement accordingto claim 1 in which at least one of the increasing means extends nearlythe full length of said hull for providing increased buoyancy andprotection thereto.
 3. An improvement according to claim 1 in which atleast one of the increasing means extends only a fraction of the lengthof said hull.